Jeremy Mortimer wrote:
"Richard Henry" wrote in
news:kzV0b.5272$QT5.899@fed1read02:

..

They're getting more and more popular in continental Europe, though
their natural habitat has to be the UK, especially dormitory towns
around London. Hemel Hempstead has a big one made out of six little
ones, which defies comprehension - I have seen cars just stop in the
middle in complete bafflement (in fact I think I might have done so
myself). When they introduced them in France they initially tried to
keep "priorité à droite", which meant cars entering had right of way;
a little thought will reveal that you only need one car at each entry
to gridlock the whole thing. They changed that eventually, but the UK
is still the only country I've driven in where people can be relied
on to understand the things (Hemel Hempstead excepted).

....and the roundabout in Hemel is a two way roundabout - it has two lanes,
one in each direction (clockwise and counterclockwise) and the little
roundabouts are likewise full duplex operations. In reality, you don't
really know you're on a big roundabout, just a series of small ones. The
bark is worse than the bite. The first time I came across it I was on a
bicycle.....

But what about Sweden? In the 60's they switched from left hand drive to
right hand drive. Overnight. Get your heads round that one! Clue: think
on/off ramps ....